Primary care physicians are in an optimal position to play an important role in health promotion and disease prevention, but few are able to routinely provide nutrition counseling even though dietary intervention is one of the main cancer prevention initiatives recommended by the National Cancer Institute. This study proposes to use patient self-help materials in dietary modification, with endorsement from the physician, as a dietary intervention in primary care practice. The philosophy of the intervention is to encourage all adults to make small changes in their fat and fiber consumption, rather than to target an intensive intervention at high risk groups. The main objective of the study is to estimate the effectiveness of this intervention in patient dietary behavior change. Clusters of physicians and nurses in Group Health Cooperative's family practice clinics in South Region, Washington State, will be contacted and invited to participate in the study. Clusters will be randomized to intervention or control group, on the under- standing that members of the control group will receive the training and access to the self-help materials at the end of the study. A program of clinician education and motivation will be implemented. A flow sheet for use when advising their patients on the use of self-help materials will be incorporated with patients' medical charts. The self-help materials will be based on "Taking Charge: Diet and Cancer" from The University of North Carolina and material used by the senior clinical nutritionists in the Women's Health Trial. They will focus on motivating specific dietary behavior changes and include step-by-step guidance for adopting the changes and integrating them into one's daily life. These will be further piloted in Washington to assess readability and usefulness. Adult patients from each study cluster will be recruited to the study and interviewed by telephone to provide a baseline assessment of their current dietary habits. Patients in the intervention clusters will be introduced to self-help materials, designed to help them lower fat and increase fiber, by the nurse or their physician. They will be reinforced in the use of the materials by a telephone follow-up call from the nurse at two weeks. Dietary habits at three month and one year follow-up will be obtained by telephone interview. The differential change in fat and fiber intake between the intervention and control groups of patients will be estimated using analysis of covariance, adjusting for within cluster correlation.